Prior art laser screens for a cathode-ray tube have semiconductor members with a reflecting coating, a cementing layer, and a transparent heat removing support with a partly transparent mirror (Ulasyuk, V. N. Kvantoskopy. [Laser Screen Cathode-Ray Tubes]. Moscow. "Radio i Svyaz" Publishing House. 1988. pp. 151-155). The cementing layer of this laser screen is located between the mirror layers so that an interface boundary extends between the semiconductor member and the cementing layer, and a partial reflection of the generated radiation from this boundary occurs.
The main disadvantage of this laser screen resides in non-uniform lasing which causes an interference pattern. This non-uniform lasing is due to the fact that generation threshold and lasing power depend on the cementing layer thickness. To avoid such non-uniformity of lasing, it is necessary that fluctuations of the layer thickness over the screen surface area, which is over 20 sq. cm, be substantially smaller than the screen lasing wavelength in this layer(&lt;.lambda./(4.multidot.N.sub.c).apprxeq.0.08 .mu.m for green light) which is practically impossible.
Another prior art laser screen for a cathode-ray tube has a semiconductor member having mirror coatings and cemented to a transparent heat removing support (Koslovsky, V. I. et al. Laser Screen of CdS, CdSSe, ZnSe. Monocrystalline Ingots Moscow. J. Kvantovaya Elektronika. 1977. Vol. 4. No. 2. p. 351). The cementing layer of this device is outside an optical cavity formed by the mirror coatings. The reflectivity of a planar wave reflected from the boundary between the cementing layer and the support is generally lower than that for the boundary between the semiconductor member and the cementing layer in the above-cited prior art laser screen. This prior art laser screen also has non-uniformity caused by dependence of generation threshold and lasing power on thickness of the cementing layer although fluctuations of the lasing power and generation threshold are lower than in the prior art device referred to above.
Attempts have been made to use a transparent heat removing support with an antireflection coating (Ulasyuk, V. N. Kvantoskopy. [Laser Screen Cathode-Ray Tubes]. Moscow. "Radio i Svyaz" Publishing House. 1988. pp. 157). The antireflection coating in this prior art laser screen was provided to prevent reflection from the boundary between the cementing layer and the support. It is, however, not possible to completely suppress reflection because of a very limited range of materials for making antireflection coatings which must have a fair adhesion to the support and an appropriate index of refraction. This is also difficult because the indices of refraction of the cementing layer and support depend on temperature, elastic stresses and quality of polish of the support. It should be noted that it is very difficult to achieve high polish of the support taking into account high hardness of materials generally used for making transparent heat removing support for laser screens (leucosapphire, garnet, etc.).